Tables and Figures

Table x (not in paper). Summary of conditions, design, and sample sizes of Experiments 1-5, and Skerry et al (2013) (SCS) Experiments 1-5, including sample size (N), what motor training procedures were used (effective sticky mittens, ineffective non-sticky mittens, or none), the goal of the person reaching (changing an object’s state, or picking it up), whether the person acted on the object in a spatiotemporally contingent manner (causal: yes, or no), and whether the person wore a mitten (yes or no). Conditions listed under a single experiment (e.g. Exp 1 and 3) included random assignment to condition. For stimuli, see Fig 1. * indicates direct replication. For stimuli, see Fig 1.

Experiment N Training Goal Habituation Causal Mitten Stimuli
1 20 none state change constrained yes yes H1, T1
1 20 none state change unconstrained yes yes H2, T1
2 20 none state change constrained no yes H3, T2
3* 26 none state change constrained yes yes H1, T1
3* 26 none state change constrained no yes H3, T2
4 20 none pick up constrained yes yes H4, T3
5 20 none pick up constrained yes no H5, T4
SCS 1 20 effective pick up constrained yes yes
SCS 2 20 ineffective pick up constrained yes yes
SCS 3 20 none pick up constrained yes yes
SCS 4* 26 effective pick up constrained yes yes
SCS 5 26 effective pick up unconstrained yes yes
Figure 1. Still frames from videos shown to participants in Experiments 1-5, including stimuli from habituation (H1-H5) and test (T1-T4). In each video, a person reached for and caused a change in an object (H1-H3, T1-T2), or picked up the object (H4-H5, T3-T4), over a barrier (H1- H2, H4-H5) or over empty space (H2, T1-T4). The person either acted on the object by contacting it (H1-H2, H4-H5, T1, T3-T4) or produced the same effect from a distance of 50 pixels, after a 0.5s delay (H3, T2), and either performed these actions while wearing a mitten (H1-H4, T1-T3) or with a bare hand (H5, T4) During test (T1-T4), the person either reached directly for the object on a novel but efficient trajectory (T1-T4, left panel), or in a curvilinear fashion on the familiar but inefficient trajectory (T1-T4, right panel).

Figure 1. Still frames from videos shown to participants in Experiments 1-5, including stimuli from habituation (H1-H5) and test (T1-T4). In each video, a person reached for and caused a change in an object (H1-H3, T1-T2), or picked up the object (H4-H5, T3-T4), over a barrier (H1- H2, H4-H5) or over empty space (H2, T1-T4). The person either acted on the object by contacting it (H1-H2, H4-H5, T1, T3-T4) or produced the same effect from a distance of 50 pixels, after a 0.5s delay (H3, T2), and either performed these actions while wearing a mitten (H1-H4, T1-T3) or with a bare hand (H5, T4) During test (T1-T4), the person either reached directly for the object on a novel but efficient trajectory (T1-T4, left panel), or in a curvilinear fashion on the familiar but inefficient trajectory (T1-T4, right panel).

Figure 2. Looking time in towards the efficient versus inefficient reach (bottom), and proportion looking towards the inefficient reach (top) at test across Experiments 1-5 (N=152). Labels above each panel list the experiment name (Exp. 1-5), type of action during habituation (constrained or unconstrained by a barrier), goal (state.change or pick.up), whether these actions involved contact with the object (yes or no), whether the actor wore a mitten (yes or no), and stimuli listed in Figure 1. Error bars around means indicate within-subjects 95% confidence intervals (bottom) and bootstrapped 95% confidence intervals (top). Individual points (top) or pairs of points (bottom) indicate data from a single participant. Horizontal bars within boxes indicate medians, and boxes indicate the middle 2 quartiles of data. Violin plots (top) indicate distribution of data, area scaled proportionally to the number of observations.

Results (Main Text)

Infants’ analysis of causal vs non-causal actions

Experiment 1

In Experiment 1 (N=40; 20 per condition), 3-month-old infants (M=107.675 days, range=91-122, 23 female) were randomly assigned to two conditions. Infants in the constrained condition viewed repeated video clips of a person who reached over a barrier that prevented direct access to the object and appeared to cause an object to light up by touching it (H1). Infants in the unconstrained condition viewed the same reaches with the barrier beyond the goal object, out of the person’s way (H2). Then infants in both conditions viewed the same pair of alternating test events, in which the barrier was removed and the person reached either efficiently on a novel, direct path or inefficiently on a familiar, indirect path (T1). Across all experiments, we calculated the average looking time towards the efficient versus inefficient unobstructed reach over 3 pairs of test events. Infant looking times are often log-normally distributed (Csibra, Hernik, Mascaro, Tatone, & Lengyel, 2016), including in this dataset (see SI), and thus were log-transformed (main analysis) or transformed to proportions (meta-analysis, see SI) prior to analysis.

A mixed effects model, including a fixed interaction between habituation and test event and a random intercept for participant identity, revealed that infants responded differently to the test events across the two conditions, [0.273,0.732], ß=0.781, B(SE)=0.502(0.114), p<.001, two-tailed, 2 participants excluded on the basis of Cook’s Distance (Nieuwenhuis, te Grotenhuis, & Pelzer, 2012). Contrasts from this model revealed that when the actor’s reaches were initially constrained by a barrier (H1), infants looked longer at the inefficient action (M=15.448s, SE=0.658) than the efficient action (M=12.368s, SE=0.658) at test, [0.396,1.139], ß=1.194, B(SE)=0.768(0.185), p<.001, two-tailed. Critically, this looking preference cannot be attributed to low-level responses to the curvilinear reach, because infants in the unconstrained condition (H2) showed a preference for the efficient (M=10.104s, SE=0.738) over the inefficient (M=8.788s, SE=0.738) action, [-0.343,-0.017], ß=-0.28, B(SE)=-0.18(0.081), p=0.032, two-tailed. See Figure 2. Experiment 1 therefore provides evidence that infants expected the actor to reach efficiently.

Experiment 2

In Experiment 2 (N=20), we asked whether this expectation depended on infants’ construal of the actor as a causal agent, who aimed to change the state of the object on contact. We manipulated the spatiotemporal continuity of the reaching action: a variable that modulates causal perception in older infants and adults and in computational studies of learning about objects and actions. Infants (M=106.7 days, range=93-121, 12 female) were habituated to videos identical to H1, except that the person’s hand stopped 50 pixels above the object (approximately 2 cm on the presentation screen), and the object illuminated after a 0.5 second delay. At test, the person reached efficiently or inefficiently in the absence of the barrier, with the same spatiotemporal gap as in habituation trials (T2). I nfants looked equally between the inefficient (M=15.306s, SE=1.123) and efficient (M=16.38s, SE=1.123) reach, [-0.191,0.301], ß=0.096, B(SE)=0.055(0.119), p=0.649, two-tailed, mixed effects model with trial type as fixed effect and participants as a random intercept. Their looking patterns differed from those of infants shown causally effective reaches in the corresponding condition of Experiment 1 (H1), [-0.623,-0.003], ß=-0.547, B(SE)=-0.313(0.154), p=0.049, two-tailed, mixed effects model with fixed interaction between causality and trial type and participants as a random intercept. This finding suggests that infants view action cost and causal efficacy as linked properties of agents’ actions.

Experiment 3

To evaluate this suggestion further, Experiment 3 (N=52; 26 per condition), pre-registered at https://osf.io/f2hvd/, attempted to replicate the findings from Experiments 1 and 2 by randomly assigning infants (M=107.154 days, range=92-121, 21 female) to these two causal conditions, thereby enabling us to compare infants’ responses to causal vs non-causal actions, using experimenters who are blind to both condition and test event information. Its findings replicated those of the previous two studies: Infants viewed the agent’s actions as efficiently directed to the goal object only when her hand contacted the object at the time of the object’s change of state, [-0.815,-0.184], ß=-0.729, B(SE)=-0.5(0.158), p=0.003, two-tailed, mixed effects model with fixed interaction of causality and test event and random intercept for participants. As in Experiment 1, infants looked longer at the inefficient reach (M=12.166s, SE=0.588) than the efficient reach (M=7.791s, SE=0.588) when the person’s actions were causally effective, [0.211,0.66], ß=0.635, B(SE)=0.436(0.112), p<.001, one-tailed, and as in Experiment 2, infants looked equally to the inefficient (M=11.395s, SE=0.818) and efficient (M=12.888s, SE=0.818) reaches when the spatiotemporal gap between her hand and the object’s illumination suggested that she did not cause this event, [-0.289,0.16], ß=-0.094, B(SE)=-0.064(0.112), p=0.284, one-tailed. Together, Experiments 1-3 show that pre-reaching infants apply the principle of efficiency to reaching actions that they themselves have never experienced, when the actions appear to cause changes in the target object. Although 3-month-old infants have limited experience acting as causal agents themselves and likely no experience illuminating objects by touching them, they apply a causal analysis to this action when it is performed by others.

Infants’ analysis of entrainment actions

Experiments 4 and 5

In Experiment 4 (N=20), infants (N=20), infants (M=107.9 days, range=92-122, 11 female) were habituated to and tested on events where a person reached for and picked up an object identical to those from Experiments 1-3 while wearing the same mitten (H4, T3), as in SCS. In Experiment 5 (N=20), infants (M=107.95 days, range=93-120, 12 female) saw almost identical videos to those from Experiment 4 except that the person reached with a bare hand (H5, T4). Infants looked longer at the inefficient (M=9.715s, SE=0.474) than the efficient (M=8.036s, SE=0.474) reach of the bare hand, [0.008,0.331], ß=0.296, B(SE)=0.17(0.08), p=0.02, one-tailed, but did not distinguish the inefficient (M=18.029s, SE=0.643) from the efficient (M=16.844s, SE=0.643) action of the mittened hand [-0.083,0.232], ß=0.13, B(SE)=0.074(0.078), p=0.172, one-tailed.

Comparing state change and entrainment actions

Across Experiments 1-5, we found that pre-reaching infants apply expectations of efficient action to a person who pursues the goal of causing a change in an object while wearing a mitten, but do not apply the same expectation to the same person wearing the same mitten when she picks up the same object. Thus, we suggest that one key difference between the state change events we used in the present experiments, and the pickup events used in SCS and Experiments 4-5, is the causal transparency of these actions: Three-month-old infants do not know how to reach for and grasp objects, and thus may struggle to understand how grasping an object could cause it to rise and move closer to the person reaching for it, thereby fulfilling the goal of the agent to retrieve it. To test this interpretation, and to assess the unique effects of our experimental manipulations and those from SCS, we performed an analysis over these two papers (total N=264, 12 conditions). Our analytic approach allows us to assess the independent effects of 5 manipulations: the type of or absence of motor training, the presence or absence of barrier preventing a direct reach for the object, the nature of the goal (to change the state of an object or pick it up), the presence or absence of action on contact, and the presence of absence of mittens on the actor. This analysis allows us to control for the participant variables age and sex, and model the nested structure of the data (e.g. looks clustered within experiments and within papers). For ease of interpretation, we use average proportion looking to the inefficient action in this analysis, following SCS. This analysis showed that infants held stronger expectations for efficient reaching when it resulted in a simple contact and state change of an object, than when it lifted and entrained the object, [0.02,0.053], ß=0.397, B(SE)=0.035(0.01), p=0.02, two-tailed. For full meta-analytic results, see SI.

Reliability (Methods Section)

To assess reliability, 50% of test trials from participants across Experiments 1-5 (132 participants, 456 trials) were randomly selected and coded by additional researchers who were unaware of experimental condition, and test trial order. The intraclass correlation coefficient (ICC) between the original data, and this newly coded data, was 0.968 [0.955, 0.978], 0.963 [0.938, 0.977], 0.936 [0.911, 0.954], 0.969 [0.946, 0.982], 0.969 [0.943, 0.982], for Experiments 1 through 5, respectively.

Supplemental Results

Comparing Experiments 4-5 with Skerry et al. (2013)

We compared the results of Experiment 4 and 5 against those from Skerry et al’s Experiment 3, wherein infants received no mittens training and viewed a person reaching with a mittened hand. The results of Experiment 5 (no mitten) differed from those of the earlier experiment (mitten), [0.047,0.547], ß=0.539, B(SE)=0.297(0.124), p=0.022, two-tailed, mixed effects model with fixed interaction between experiment and test event and random intercept for participants, one influential participant excluded on the basis of Cook’s Distance, whereas the results from Experiment 4 (mitten) marginally differed from those in of Skerry et al. (mitten), [-0.021,0.47], ß=0.43, B(SE)=0.224(0.122), p=0.074, two-tailed, mixed effects model with fixed interaction between experiment and test events and random intercept for participants, 2 influential participants excluded on the basis of Cook’s Distance.

Meta-analytic results

To assess the unique effects of our experimental manipulations in Experiments 1-5 and in SCS, we performed an analysis over these two papers (total N=264, 12 conditions). We assess the independent effects of 5 manipulations (see Figure S1) while controlling participant variables age and sex, and modeling the nested structure of the data. For ease of interpretation, we used average proportion looking to the inefficient action in this analysis, following SCS.

This analysis confirmed that first-person action experience is not the only way to enhance infants’ appreciation of the causal and intentional aspects of action. It also confirmed the findings from the individual experiments reported in the main text and from SCS: Infants’ expectations were stronger when the observed action was spatiotemporally continuous its effect (i.e., appeared to be causal), [0.027,0.06], ß=0.501, B(SE)=0.044(0.009), p<.001, two-tailed, when infants received effective motor training (sticky mittens), relative to no training [0.027,0.069], ß=0.558, B(SE)=0.049(0.011), p=0.003, two-tailed, when the observed agent’s actions were constrained by a barrier and were efficiently adapted to that barrier, relative to the same actions that were unconstrained by a barrier, [0.021,0.051], ß=0.407, B(SE)=0.036(0.008), p=0.001, two-tailed, and when the agent pursued a state change goal, relative to a pickup goal, [0.02,0.053], ß=0.397, B(SE)=0.035(0.01), p=0.02, two-tailed. We also found that infants’ expectations were marginally negatively affected when they received ineffective motor training (non-sticky mittens), relative to no training, [-0.06,-0.005], ß=-0.354, B(SE)=-0.031(0.015), p=0.068, two-tailed, and were unaffected when the actor wore a mitten, relative to no mitten [-0.045,0], ß=-0.232, B(SE)=-0.021(0.012), p=0.14, two-tailed.

Figure S1. Looking time in towards the efficient versus inefficient reach (bottom), and proportion looking towards the inefficient reach (top) at test across Experiments 1-5 (n=152) and across Experiments 1-5 in Skerry et al. (2013) (n=112). Labels above each panel list the experiment name (Exp. 1-5, SCS Exp. 1-5), type of motor training (none, ineffective non-sticky mittens, or effective sticky mittens), type of action during habituation (constrained or unconstrained by a barrier), goal (state.change or pick.up), whether actions resulted in contact with the object (yes or no), whether the actor wore a mitten (yes or no), and stimuli listed in Figure 1. Error bars around means indicate within-subjects 95% confidence intervals (bottom) and bootstrapped 95% confidence intervals (top). Individual points (top) or pairs of points (bottom) indicate data from a single participant. Horizontal bars within boxes indicate medians, and boxes indicate the middle 2 quartiles of data. Violin plots (top) indicate distribution of data, area scaled proportionally to the number of observations.

Figure S2. Effect plots for model investigating predictors of sensitivity to action efficiency across Experiments 1-5 and Skerry et al. (2013) (total N=264, 247 included in final analysis, 17 excluded on the basis of Cook’s Distance). Each point shows estimates of effects at each level of all categorical predictors: Type of motor training (none, ineffective non-sticky mittens, or effective sticky mittens), the goal of the actor (state change vs pick up), action during habituation (constrained or unconstrained by a barrier), whether actions resulted in contact with the object (yes or no), whether the actor wore a mitten (yes or no). Error bars indicate 95% confidence intervals. See Table S1 for full results.

Table S1. Regression table for model investigating predictors of sensitivity to action efficiency across Experiment 1-5 and all experiments from Skerry et al. (2013) (total N=264, 247 included in final analysis, 17 excluded on the basis of Cook’s Distance). Dependent measure is proportion looking towards the inefficient reach, averaged across 3 test trials during test. Categorical predictors were coded using sum contrasts, and fixed effects from the model should therefore be interpreted with respect to the grand mean (i.e. with respect to 0). Degrees of freedom were generated using the Satterthwaite approximation method. Model formula: prop.ineff.all ~ training + goal + hab + causal + mitten + (1|experiment) + (1|ageday) + (1|sex) + (1|paper).

Standardized Estimate (ß) Estimate (B) Standard Error (SE) df t p 95% CI (Lower) 95% CI (Upper)
(Intercept) -0.340 0.488 0.019 2.19 25.28 0.001 0.457 0.523
effective training 0.558 0.049 0.011 7.32 4.31 0.003 0.027 0.069
ineffective training -0.354 -0.031 0.015 8.70 -2.08 0.068 -0.060 -0.005
state change goal 0.397 0.035 0.010 4.24 3.66 0.020 0.020 0.053
constrained habituation 0.407 0.036 0.008 9.61 4.54 0.001 0.021 0.051
causally effective 0.501 0.044 0.009 20.54 5.08 0.000 0.027 0.060
mitten -0.232 -0.021 0.012 7.39 -1.65 0.140 -0.045 0.000

This analysis confirmed that first-person action experience is not the only way to enhance infants’ appreciation of the causal and intentional aspects of action. It also confirmed the findings from the individual experiments reported in the main text and from Skerry et al. (2013): Infants’ expectations were stronger when the observed action was spatiotemporally continuous with its effect (i.e., appeared to be causal),[0.027,0.06], ß=0.501, B(SE)=0.044(0.009), p<.001, two-tailed, when infants received effective motor training (sticky mittens), relative to no training, [0.027,0.069], ß=0.558, B(SE)=0.049(0.011), p=0.003, two-tailed, when the observed agent’s actions were constrained by a barrier and were efficiently adapted to that barrier, relative to the same actions that were unconstrained by a barrier, [0.021,0.051], ß=0.407, B(SE)=0.036(0.008), p=0.001, two-tailed, and when the agent pursued a state change goal, relative to a pickup goal, [0.02,0.053], ß=0.397, B(SE)=0.035(0.01), p=0.02, two-tailed. We also found that infants’ expectations were marginally negatively affected when they received ineffective motor training (non-sticky mittens), relative to no training, [-0.06,-0.005], ß=-0.354, B(SE)=-0.031(0.015), p=0.068, two-tailed, and were unaffected when the actor wore a mitten, relative to no mitten [-0.045,0], ß=-0.232, B(SE)=-0.021(0.012), p=0.14, two-tailed, as reported in the main text.

Exclusion info

Table S2. Tally of infants who participated in Experiments 1-5 but were excluded in our final sample. These exclusion criteria were set prior to the start of data collection, but vary slightly by experiment (e.g. we relaxed our definition of inattentiveness from excluding all data from a participant if they missed a test trial in Experiment 1, to excluding data from just that trial in Experiments 2-5).

Experiment Fussiness Inattentiveness Caregiver Interference Experimenter/Coding Error Technical Failure Total
Exp.1 9 5 1 12 3 30
Exp.2 0 0 0 2 0 2
Exp.3 6 0 0 2 0 8
Exp.4 7 0 0 2 0 7
Exp.5 6 0 0 1 2 9
Total 28 5 1 19 5 50

Distribution of Looks

Figure S3. Density plot of looking times during test across Experiments 1-5, and Experiments 1-5 from Skerry et al. (2013) (N=264). Maximum-likelihood fitting revealed that the lognormal distribution (log likelihood=-1720.509) provides a better fit to these data than the normal distribution (log likelihood=-1842.196).

Reliability

Figure S4. Discrepancy between original and new coding of looking times during test trials in seconds.

Attention during habituation across Exp 1-5

Figure S5. Total looking time in seconds during habituation across Experiment 1-5. Error bars around means indicate bootstrapped 95% confidence intervals. Individual points indicate data from a single participant. Horizontal bars within boxes indicate medians, and boxes indicate the middle 2 quartiles of data. Violin plots in indicate distribution of data, area scaled proportionally to the number of observations.

Figure S6. Looking time in seconds during each habituation trial across Experiment 1-5. Curves with 95% confidence interval ribbons indicate smoothed conditional means, generated using the loess method. Connected points indicate data from a single participant.

Tables S4-S8 Regression table for mixed effects model analyzing the effect of age, sex, order of test events, habituation condition, goal, mitten, and causal information on habituation, controlling for variations across Experiments 1-5. Model formula: total_hab ~ ageday + sex + first.test + hab + goal + mitten + causal + (1|experiment)

Standardized Estimate (ß) Estimate (B) Standard Error (SE) df t p 95% CI (Lower) 95% CI (Upper)
(Intercept) -0.208 343.171 76.54 151.82 4.483 0.000 192.192 494.168
Age in Days -0.233 -2.058 0.68 147.57 -3.026 0.003 -3.400 -0.714
Sex 0.066 5.203 6.11 148.69 0.852 0.396 -6.916 17.274
First Test Event -0.006 -0.439 6.00 146.69 -0.073 0.942 -12.270 11.393
Habituation 0.222 17.590 11.03 131.60 1.595 0.113 -6.441 41.220
Goal 0.007 0.589 16.02 6.18 0.037 0.972 -0.777 50.348
Mitten 0.126 9.996 19.02 5.73 0.525 0.619 8.336 50.922
Causal -0.055 -4.379 9.08 75.38 -0.482 0.631 -5.024 3.212

To ask whether infants’ attention during habituation was affected by experimental manipulations across Experiment 1-5 (constrained vs unconstrained habituation, state change vs pickup goal, mitten vs no mitten, and causally contingent vs noncontigent action), and varied by gender and age, we fit a mixed effects model on these fixed effects and experiment (1-5) as a random intercept. We found that the only robust predictor of attention during habituation was age, [-3.4,-0.714], ß=-0.233, B(SE)=-2.058(0.68), p=0.003, two-tailed, such that older infants looked for a shorter time overall than younger infants.

Exploring effect of test trial order, attention during habituation, age in days, and sex across Exp 1-5

To explore the additional effects of test trial order (inefficient or efficient first), attention during habituation, age in days, and sex on attention during test, we ran one linear model per experiment including an interaction between test event order and test event in Experiments 2, 4, and 5, an interaction between these factors and habituation in Experiment 1, and an interaction between these factors and causal contingency in Experiment 3.

Regression tables (Tables S4-8) and effect plots (Figures S7-S11) for each of these models are below. In general, we found no effect of sex or age, and for all experiments, we found that infants who looked longer during habituation also were more attentive during test. In addition, the infants in Experiment 1 who were randomly assigned to habituate to a constrained action look longer overall at test, [0.022,0.28], ß=0.233, B(SE)=0.151(0.064), p=0.024, two-tailed. In Experiments 1 and 2, we also found that infants randomly assigned to view the efficient reach first looked longer overall at test. No other significant effects emerged.

Tables S3-S7. Regression tables from exploratory models in Experiments 1-5. Dependent measure is log-tranforming looking times at test, averaged across 3 test pairs. Categorical predictors were coded using sum contrasts, and fixed effects from the model should therefore be interpreted with respect to the grand mean (i.e. with respect to 0). Model formulas are listed above each table. See Figures S4-S8.

Figures S7-S11. Effect plots for model investigating exploratory and hypothesis-driven predictors of sensitivity to action efficiency across Experiments 1-5. Each point shows estimates of effects at each level of all categorical predictors. Error bars and ribbons indicate 95% confidence intervals. See Tables S3-S7 for full results.

Experiment 1

Model formula: loglook ~ hab * type * first.test + total_hab + sex + ageday + (1|subj_id)

Standardized Estimate (ß) Estimate (B) Standard Error (SE) df t p 95% CI (Lower) 95% CI (Upper)
Intercept 0.012 2.579 0.941 40 2.739 0.009 0.689 4.469
Habituation 0.233 0.151 0.064 40 2.350 0.024 0.022 0.280
Test Event 0.050 0.032 0.033 40 0.978 0.334 -0.034 0.099
First Test Event 0.227 0.147 0.064 40 2.289 0.027 0.018 0.276
Attention During Habituation 0.463 0.003 0.001 40 3.564 0.001 0.001 0.004
Sex -0.082 -0.053 0.065 40 -0.815 0.420 -0.185 0.078
Age in Days -0.113 -0.007 0.008 40 -0.923 0.362 -0.023 0.009
Habituation:Test Event 0.149 0.096 0.033 40 2.923 0.006 0.030 0.163
Habituation:First Test Event 0.052 0.034 0.064 40 0.529 0.600 -0.094 0.161
Test Event:First Test Event -0.069 -0.045 0.033 40 -1.354 0.183 -0.111 0.022
Habituation:Test Event:First Test Event -0.002 -0.001 0.033 40 -0.032 0.974 -0.067 0.065

Experiment 2

Model formula: loglook ~ type * first.test + total_hab + sex + ageday + (1|subj_id)

Standardized Estimate (ß) Estimate (B) Standard Error (SE) df t p 95% CI (Lower) 95% CI (Upper)
Intercept -0.022 2.680 0.780 20 3.434 0.003 1.074 4.286
Test Event -0.048 -0.028 0.060 20 -0.464 0.648 -0.148 0.093
First Test Event -0.356 -0.205 0.067 20 -3.045 0.006 -0.339 -0.072
Attention During Habituation 0.502 0.003 0.001 20 4.146 0.000 0.002 0.005
Sex 0.110 0.064 0.064 20 0.999 0.330 -0.063 0.190
Age in Days -0.085 -0.006 0.007 20 -0.772 0.449 -0.020 0.009
Test Event:First Test Event -0.036 -0.021 0.060 20 -0.352 0.728 -0.142 0.100

Experiment 3

Model formula: loglook ~ causal * type * first.test + total_hab + sex + ageday + (1|subj_id)

Standardized Estimate (ß) Estimate (B) Standard Error (SE) df t p 95% CI (Lower) 95% CI (Upper)
Intercept 0.012 2.310 0.897 52 2.576 0.013 0.519 4.101
Causal 0.097 0.067 0.073 52 0.919 0.363 -0.078 0.212
Test Event 0.135 0.093 0.038 52 2.444 0.018 0.017 0.169
First Test Event -0.063 -0.043 0.071 52 -0.602 0.550 -0.185 0.099
Attention During Habituation 0.428 0.005 0.001 52 4.054 0.000 0.003 0.008
Sex 0.065 0.044 0.075 52 0.594 0.555 -0.105 0.194
Age in Days -0.092 -0.007 0.008 52 -0.830 0.410 -0.023 0.010
Causal:Test Event -0.182 -0.125 0.038 52 -3.292 0.002 -0.201 -0.049
Causal:First Test Event 0.052 0.036 0.072 52 0.503 0.617 -0.107 0.179
Test Event: First Test Event -0.115 -0.079 0.038 52 -2.074 0.043 -0.155 -0.003
Causal:Test Event:First Test Event 0.004 0.003 0.038 52 0.078 0.938 -0.073 0.079

Experiment 4

Model formula: loglook ~ type * first.test + total_hab + sex + ageday + (1|subj_id)

Standardized Estimate (ß) Estimate (B) Standard Error (SE) df t p 95% CI (Lower) 95% CI (Upper)
Intercept -0.008 1.907 1.051 20 1.815 0.085 -0.255 4.070
Test Event 0.020 0.010 0.040 20 0.247 0.807 -0.073 0.093
First Test Event -0.190 -0.093 0.077 20 -1.215 0.239 -0.252 0.065
Attention During Habituation 0.650 0.005 0.001 20 4.163 0.000 0.002 0.007
Sex 0.079 0.039 0.073 20 0.533 0.600 -0.111 0.188
Age in Days 0.019 0.001 0.010 20 0.130 0.898 -0.018 0.021
Test Event:First Test Event -0.201 -0.099 0.040 20 -2.453 0.023 -0.182 -0.016

Experiment 5

Model formula: loglook ~ type * first.test + total_hab + sex + ageday + (1|subj_id)

Standardized Estimate (ß) Estimate (B) Standard Error (SE) df t p 95% CI (Lower) 95% CI (Upper)
Intercept -0.024 0.901 1.221 20 0.738 0.469 -1.611 3.414
Test Event 0.148 0.074 0.041 20 1.782 0.090 -0.011 0.158
First Test Event 0.052 0.026 0.081 20 0.322 0.751 -0.140 0.192
Attention During Habituation 0.596 0.005 0.001 20 3.578 0.002 0.002 0.008
Sex 0.118 0.059 0.080 20 0.736 0.470 -0.105 0.222
Age in Days 0.071 0.005 0.011 20 0.429 0.673 -0.017 0.027
Test Event:First Test Event -0.035 -0.017 0.041 20 -0.419 0.680 -0.102 0.068